Honda VF 700 C Magna vs Yamaha XJ 700 S Maxim

Joo ja sen verran korjausta että nelisylinterisiä nämä molemmat ovat

LÖYTYIKIN jo tietoa, tosin se käyttäjien kokemukset puuttuu:

Bright Lights: A Comparison of
Honda V45 Magna vs Yamaha 750 Maxim-X

Pick your own proportion of luxury and performance for the street.
Honda's hold on the 750 custom market in Canada has been overpowering in recent years, and much of that success has been won by the V45 Magna. For '85, the Magna has been given a minor face lift; its popularity doesn't warrant extensive changes.

Yamaha, on the other hand, needed something special to crack Honda's sales grip. In a bold move, Yamaha slipped its most potent engine technology into the conservative Maxim styling package, hoping that an explosive amount of horsepower would shatter the Magna's status as reigning high-tech street cruiser. The question remians, however, whether Yamaha has succeeded in upsetting the Magna from its throne or in simply establishing a brand-new category of machine.

Even though these two bikes ostensibly share the same class, they differ radically in design, performance and style. The '85 Magna's updated cosmetics are a closer reworking of the Harley-Davidson look. The seat has been lowered, the wheelbase stretched and a new backrest added. The Maxim-X is a typical representative of Japanese inline-four customs. Its wheelbase is shorter, the steering head high and the front fork very long. In contrast with some of the more successful Harley clones, the Maxim[-X]'s custom styling appears a little dated.

There's certainly nothing dated about the Maxim-X's engine design. The cylinder and cylinder head are virtually identical to the FZ750's, but are mounted on crankcases derived from the air-cooled XJ900. The advantages of a five-valve cylinder head design have been extolled in Cycle Canada in the April and June issues. To recap them, the five valves allow the included valve angle to be narrowed while maintaining sufficient intake area for high rpm breathing without the need for radical camshafts. The low valve angle permits a high compression ratio without the onset of detonation. The theoretical results of this design are a wide powerband and a high peak power output.

Except for the changes required by the Maxim[-X]'s [nearly] upright cylinder block, the FZ and Maxim[-X] powerplants are the same. Both use 33mm constant velocity carburetors, the Maxim[-X]'s being the sidedraft variety while the FZ's are downdraft. The three 21mm intake and two 23mm exhaust valves are the same on both engines, as are the included valve angles. The resulting shallow combustion chamber allows a high compression ratio of 11.2:1 without requiring the use of premium gas. The camshaft specs also remain identical, with 276 degrees of intake and exhaust duration, and lift of 7.6mm and 7.4mm for the intake and exhaust valves, respectively.

The bottom end of the Maxim-X's powerplant is based on the XJ900's crankcase, with the necessary changes to incorporate liquid cooling. The cylinders a canted forward 14 degrees rather than the 45 degrees of the FZ750, requiring a new lower cylinder head tier to accommodate horizontal intake ports and sidedraft carburetors. The different exhaust system and induction system with its curved ports result in a lower peak power of 90hp at 9000rpm compared with the FZ's peak of 102hp.

The Honda's 90-degree V4 powerplant, first introduced in '82, has become the cornerstone of Honda's street bike line. Although three years is a long time for a motorcycle engine to remain unchanged in these days of rapid technical advances, a quick review of the V45's engine specs reveals a thoroughly modern powerplant. The bore and stroke are an extremely oversquare 70.0mm x 48.6mm, allowing the large paired 26mm intake and twin 23mm exhaust valves. Liquid cooling and the low included valve angle of 38 degrees permit the high compression ratio of 10.5:1 without the onset of detonation, and 32mm constant velocity carburetors complete the intake system.

The [Maxim-X and Magna] engines are as different in character as they are in design. The V45's mile-wide powerband has endeared it to thousands of riders, sporting and cruiser enthusiasts alike. Good power starts at 2000rpm and continues all the way to the 9800rpm redline and beyond. There is no discernible step in the powerband, just a linear progression in power as the revs increase. The smooth powerband and the lack of vibration at any engine speed give the Magna an impression of relaxed competence.

A rider error at the drag strip resulted in a burnt clutch on the V45, and we weren't able to record a representative quarter mile time. However, the Magna delivers more than enough power for its intended purpose. Acceleration around town is authoritative, and passing power is readily available if the rider down-shifts to fifth gear. Overdrive has the engine spinning at such low revs that there is simply not enough torque to provide quick passing.

The carburetion on our Honda was a little rough when we picked it up and it stalled repeat